Arthroscopic tunnel guide for rotator cuff repair

ABSTRACT

A drill guide assembly for drilling a tunnel having a fixed, non-zero radius of curvature, where the drill guide assembly includes a housing and a sleeve, or cutting tube, configured to reciprocate within the distal portion where the sleeve, or cutting tube, is configured to receive a bone cutting instrument.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.61/147,565 filed Jan. 27, 2009, and U.S. Provisional Application No.61/231,279 filed Aug. 4, 2009, the entirety of each application isincorporated herein by reference.

BACKGROUND

Traditional methods of tissue repair to the shoulder or other jointareas are accomplished through open surgery. For example, rotator cuffrepair is a type of surgery to fix a torn tendon in the shoulder. Therotator cuff is a group of muscles and tendons which form a covering, ora “cuff,” around the top of the upper arm bone, referred to as thehumerus. The rotator cuff holds the humeral head in place in theshoulder joint and enables the arm to elevate and rotate.

The rotator cuff may tear through a single traumatic injury or overuse.A partial tear may require only a trimming or smoothing procedurereferred to as a “debridement.” A complete tear, however, may berepaired by suturing the two sides of the tendon back together.Moreover, if the tendon is torn away from a location referred to as thegreater tuberosity atop the humerus, it is reattached directly back tothe humerus.

One method to attach the tendon back to the humerus is accomplishedthrough open surgery. Open surgery requires the surgeon to make a two tothree-inch incision in the shoulder area. The deltoid muscle is then cutthrough and/or separated in order to gain access to the damaged tendon.A small trough at the top of the humerus is created and small holes aredrilled therethrough. Transosseous sutures are weaved or stitchedthrough the rotator cuff and passed through the small holes to securethe rotator cuff to the humerus. Alternatively, anchors may be used toattach the tendon to the humerus. Although an effective method ofrepairing detached rotator cuff tendons, open surgery is not without itsconsequences. Pain, swelling, increased chance of infection, andprolonged recovery times are just a few examples of the adverse effectsof open surgery.

To reduce the complications associated with open surgery, another methodof repairing a torn rotator cuff is preformed arthroscopically.Arthroscopic surgery has some advantages as a result of its minimallyinvasive nature. Thus, the risks of infection, blood loss, and the like,are lower than compared to open surgery. However, because the incisionsmade during arthroscopic surgery are typically six to eight millimeterswide, the instruments used to repair the rotator cuff are more limitedin size.

For example, suture anchors are commonly used in arthroscopic surgery torepair the rotator cuff tears. A suture anchor is configured to besecured into the humeral head and is designed to attach a portion of thedamaged or torn rotator cuff to the greater tuberosity of the humeralhead. The anchor portion is embedded into the bone and has at least onesuture attached thereto. The suture extends from the anchor and securesthe damaged rotator cuff tendon to the greater tuberosity of the humeralhead.

However, in some patients, the bone quality in the greater tuberositymay be poor, thereby inhibiting, or providing less optimal, securementof the suture anchors within the humeral head. In such situations, thechances of bone fragmentation and anchor displacement may affect theintegrity of the repair.

Attempts have also been made to use the techniques of open surgeryrepair, arthroscopically. For example, others have attempted toaccomplish arthroscopic repair of the rotator cuff tendons through thebone tunnel and suture method explained above. However, the upper limitson the size of the available instruments which may be used to form bonetunnels are restricted by the diameters of the arthroscopic portals.

BRIEF SUMMARY

In order to address the drawbacks with open surgical techniques and thearthroscopic attachment devices discussed above, an orthopedic drillguide assembly having a sleeve with a fixed radius of curvature to forma tunnel within a bone is disclosed. In one embodiment, an orthopedicdrill guide assembly for drilling a tunnel in a bone includes a drillguide housing having a proximal portion, a distal portion, where thedistal portion is curved in shape. A body portion is disposed betweenthe proximal portion and the distal portion. A passage is formed withinthe drill guide housing and extends from the proximal portion to thedistal portion such that the passage has a fixed radius of curvaturewithin the distal portion. A sleeve having a lumen therethrough, wherethe sleeve has a proximal end and a distal end, is slidingly disposedwithin the passage of the distal portion of the drill guide housing andhas a fixed radius of curvature which is substantially equal to theradius of curvature of the passage within the distal portion. The sleeveis configured to extend from the distal portion and further configuredto receive a bone cutting instrument.

In another embodiment, an orthopedic drill guide assembly for drilling atunnel in a bone includes a drill guide housing having a proximalportion and a distal portion. A body portion is disposed between theproximal portion and the distal portion and a passage is formed withinthe drill guide housing and extending from the proximal portion to thedistal portion. A tube is slidingly disposed within the passage of thedistal portion of the drill guide housing and has a lumen therethroughand having a proximal end and a distal end. The tube is made out of ashape memory alloy and can to extend from the distal portion and furtherconfigured to receive a bone cutting instrument.

A method of arthroscopically drilling a tunnel through a bone includesproviding a drill guide with a drill guide housing having a distalportion, a sleeve slidingly disposed within the drill guide housing, aflexible shaft disposed within the drill guide housing and coupled withthe sleeve, and a bone cutting tip coupled to at least one of the distalend of the flexible shaft and/or the sleeve. The distal portion of thedrill guide housing is placed against a desired entry port location onthe bone and the bone cutting tip and sleeve are advanced into the bone,where the bone cutting tip travels along a fixed non-zero radius ofcurvature defined by the sleeve. A tunnel is created within the bonehaving a fixed non-zero radius of curvature substantially equal to thefixed non-zero radius of curvature of the sleeve.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is perspective view of one embodiment of the drill guideassembly.

FIG. 2 is a perspective view of one embodiment of the distal end of thedrill guide housing.

FIG. 3 is a perspective view of one embodiment of the sleeve.

FIG. 4 is a perspective view of one embodiment of the sleeve.

FIG. 5 is a perspective view of one embodiment of the distal end of thedrill guide housing.

FIG. 6 is an exploded view of one embodiment of the distal end of thedrill guide housing.

FIG. 7 is a frontal view of one embodiment of the sleeve.

FIG. 8 is a cross-sectional view of the distal portion of the drillguide housing.

FIG. 9A is a perspective view of one embodiment of the sleeve.

FIG. 9B is a fragmentary view of one embodiment of the sleeve.

FIG. 9C is another fragmentary view of the embodiment of the sleeveshown in FIG. 9B.

FIG. 10 is a cross-sectional view of one embodiment of the fastener.

FIG. 11 is a front view of one embodiment of the stop member.

FIG. 12 is a perspective view of the medial patellofemoral ligamentgraft.

FIG. 13 is a fragmentary view of another embodiment of the drill guideassembly in a retracted position.

FIG. 14 is a fragmentary view of the embodiment of the drill guideassembly shown in FIG. 13 in an advanced position.

FIG. 15 is a fragmentary view of a distal end of the embodiment of thedrill guide assembly shown in FIG. 13 adjacent to the humeral head of apatient.

FIG. 16 is a fragmentary view of the distal end of the embodiment of thedrill guide assembly shown in FIG. 13 advanced through the humeral headof the patient.

FIG. 17 is a fragmentary view of the distal end of the embodiment of thedrill guide assembly shown in FIG. 13 in a retracted position adjacentto the humeral head of the patient.

FIG. 18 is a fragmentary view of the cutting tube of the embodiment ofthe drill guide assembly shown in FIG. 13.

FIG. 19 is a fragmentary view of another embodiment of the drill guideassembly.

FIG. 20 is a fragmentary view of yet another embodiment of the drillguide assembly.

FIG. 21 is a fragmentary view of yet another embodiment of the drillguide assembly.

DETAILED DESCRIPTION

The embodiments below are described with reference to the drawings inwhich like elements are referred to by like numerals. The relationshipand functioning of the various elements are better understood by thefollowing detailed description. However, the embodiments as describedbelow are by way of example only, and the invention is not limited tothe embodiments illustrated in the drawings.

Throughout this specification and in the appended claims the term“distal” with respect to such a device is intended to refer to alocation, or a portion of the device, that is further away from the userof the device. The term “proximal” is intended to refer to a location,or a portion of the device, that is closer to the user of the device.

The embodiments of the orthopedic guide device described below areconfigured to create tunnels with a substantially fixed and constantradius of curvature within a bone, and to permit a suture, or fasteningdevice similar thereto, to be disposed through the tunnel to secure aportion of a ligament, tendon, a bone, or other various parts of theanatomy.

In one embodiment, and as shown in FIG. 1, a drill guide assembly 10 isshown. The drill guide assembly 10 consists of a housing 12 defining anA axis. The drill guide assembly 10 comprises a proximal portion 14, adistal portion 16, and a body portion 18 disposed between the proximal14 and distal 16 portions. The relative lengths of the proximal 14,distal 16, and body 18 portions may vary between applications, and maybe dependent on the desired maneuverability and characteristics for aparticular use.

In the embodiment shown in FIG. 1, the body portion 18 has asubstantially linear shape, however, the shape of the body portion 18may vary depending on the intended use of the assembly 10. For example,the body portion 18 may also have a shape having a non-zero radius ofcurvature, for improved ergonomics or use during operation.

A handle 20 may form a part of the proximal portion 14 for gripping thehousing 12. The handle 20 may have a series of indentations 22 or have agripping material located thereon in order to accommodate a user's hand.The handle 20 may also be located on any other portion of the housing12. For example, the handle 20 may form a part of the body portion 18 toprovide more controlled movement of the drill guide assembly 10 duringuse.

As further shown in FIG. 1, a passage 24 is formed within the housing12. The passage 24 generally extends from the proximal portion 14 of thehousing 12 to the distal portion 16 of the housing 12, along the A axis.The passage 24 is configured to accommodate a flexible shaft 26, such asa guide wire or the like, such that the flexible shaft 26 can rotateand/or reciprocate within the passage 24. The diameter andcross-sectional shape of the flexible shaft 26 and/or passage 24 mayvary along the length of the housing 12. Moreover, the passage 24 mayonly extend along a portion of the housing 12 such that an entrance maybe formed along any portion of the housing 12 to allow the flexibleshaft 26 to enter the housing 12. The passage 24 and/or the flexibleshaft 26 may be coated with a lubricating compound, such as graphite orTeflon, or be made out of a material having a low coefficient offriction to reduce the frictional force generated by the relativemovement between the passage 24 and the flexible shaft 26. Suchmaterials include metal alloys and plastics.

As shown in FIGS. 1 and 2, the distal portion 16 of the housing 12 maybe curved in shape. The angular displacement and radius of curvature, R,of the distal potion 16 may vary between each embodiment and isapplication dependent. However, the radius of curvature for the distalportion 16 will remain substantially constant within each embodiment.The distal portion 16 may have an arc-shape ranging from 0 to 300degrees, and the fixed non-zero radius of curvature may be 0 to 50 mm.However, the exact radius of curvature desired is dependent on the bonethickness and the intended use. For example, in the embodiment shown inFIG. 2, the distal portion 16 of the housing 12 has a semi-circularshape with a constant radius of curvature, R.

The passage 24 formed within the distal portion 16 of the housing 12 mayhave a shape and a radius of curvature similar to that of the distalportion 16. As shown in FIGS. 1 and 2, the passage 24 within the distalportion 16 is designed to accommodate a sleeve 28. The sleeve 28 isconfigured to reciprocate within, and extend from, the distal portion 16of the housing 12. The sleeve 28 has a proximal end 30 and a distal end32, defining a lumen 34 therethrough. The sleeve 28 may be made out of amaterial similar to that of the housing 12. The radius of curvature ofthe sleeve 28 is substantially equal to the radius of curvature of thepassage 24 of the distal portion 16 of the housing 12. Although thelength of the sleeve 28 may vary, its maximum length, in the embodimentsof FIGS. 1 and 2, is limited to the circumferential length of the distalportion 16 and has substantially the same radius of curvature as thedistal portion 16.

The sleeve 28 is configured to accommodate a bone cutting tip 56. Thebone cutting tip 56 is disposed on a distal end 54 of the flexible shaft26. The bone cutting tip 56 is designed to create a hole, or tunnel 94,having approximately the same diameter of the bone cutting tip 56through a medium, such as bone. As shown in FIGS. 3 and 4, the bonecutting tip 56 is fixedly coupled with the distal end 54 of the flexibleshaft 26, with the bone cutting tip 56 being disposed adjacent to thedistal end 32 of the sleeve 28. The bone cutting tip 56 and the flexibleshaft 26 are configured to be able to rotate with respect to the sleeve28. The bone cutting tip 56 forms a hole having a diameter which is atleast equal to the outer diameter of the sleeve 28, to permit the sleeve28 to be advanced through the hole or tunnel 94 formed within theworking medium. The bone cutting tip 56 may be formed out of anysuitable metal alloy or plastic.

Turning back to FIG. 1, an outer stop member 70 is located along theflexible shaft 26 at a location proximal to the proximal portion 14 ofthe housing 12. The outer stop member 70 is configured to abut anexternal surface of the proximal portion 14 of the housing 12 to limitthe distance the flexible shaft 26 and/or sleeve 28 may travel withinthe housing 12. However, the location of the outer stop member 70 isdependent on the entrance location of the flexible shaft 26 with respectto the housing 12; and thus it is not necessary that the outer stopmember 70 is positioned at a location proximal to the proximal portion14 of the housing 12. A series of graduated markings may be positionedalong the flexible shaft 26 and viewable external to the housing 12 toindicate the amount of linear or angular displacement of the bonecutting tip 56 with respect to the housing 12.

Located along the body portion 18 of the housing 12, and configured toreciprocate along, and extend from, the housing 12, there may be an exitport locator 76, as shown in FIG. 1. The exit port locator 76 has afirst end 78 and a second end 80. The first end 78 of the exit portlocator 76 is coupled with the body portion 18 of the housing 12, and isconfigured to slide along the body portion 18 from a retracted positionwhere the second end 80 of the exit port locator 76 is adjacent to, andin contact with, the body portion 18, to a second position, where thesecond end 80 is fully extended from the body portion 18. In the secondposition, which is shown in FIG. 1, the location second end 80 of theexit port locator 76 is approximately the same location where the bonecutting tip 56 would be located when it is extended and rotatedapproximately 90° from the distal portion 16 of the housing 12.Accordingly, the second end 80 of the exit port locator 76, when in thesecond position, identifies the exit location of the tunnel 94 oraperture prior to the commencement of the drilling process. The exitport locator 76 may also be used to secure the drill guide assembly 10during the drilling process. For ease of identification, the second end80 may be L-shaped or have radiopaque markers to aid in locating thesecond end 80 during operation. The exit port locator 76 may be made outof the same material as the housing 12 or any other material which issuitable for surgical use. The exit port locator 76 may be spring loadedor have a locking mechanism to lock the exit port locator 76 when in thefirst and/or second position, or any position therebetween.

Turning now to FIG. 5, it can be appreciated that the orientation of thedistal portion 16 may vary with respect to the housing 12. The differentconfigurations of the distal portion 16 may cause the configuration ofthe exit port locator 76 to change. For example, in this embodiment,distal portion 16 has a semicircular shape defined along a vertical axisB, where the axis A of the housing 12 is substantially perpendicular tothe vertical axis B. It can be appreciated that the body portion 18 ofthe housing 12 may be positioned in any location along the curve of thedistal portion 16, depending on the intended use of the drill guideassembly 10.

In an alternative embodiment, as shown in FIG. 6, the body portion 18 ofthe housing 12 may have an aperture 36, from which a proximal end 30 ofthe sleeve 28 may extend from. In this embodiment, the length of thesleeve 28 may be greater than the circumferential length of the distalportion 16. Further, as shown in the FIG. 7 embodiment, the sleeve 28may have a channel 52 formed at least partially along the length of thesleeve 28. The diameter of the channel 52 is at least wide enough toreceive the flexible shaft 26. The channel 52 permits the flexible shaftto enter the sleeve 28 at a location other than through the proximal end30 of the sleeve 28 as was the case in the embodiment of FIG. 1. Thechannel 52 may be formed along a portion or the entire length of thesleeve 28. The exact width and length of the channel 52 will be dictatedby the size of the flexible shaft 26 and the intended use of the drillguide assembly 10.

A channel and a guide configuration may prevent unwanted relativerotational movement between the sleeve 28 and the distal portion 16 ofthe housing 12, which could bind the sleeve 28 within the distal portion16 during operation. For example, one configuration is shown in FIG. 8,which is a cross-sectional view of the distal portion 16 of the housing12 and the sleeve 28 taken along the line 8-8 of FIG. 3. As shown inFIG. 8, the sleeve 28 may include a guide 72, external thereto,extending along at least a portion of the sleeve 28. A channel 74 may beformed within the distal portion 16 of the housing 12 which is alignedwith, and is configured to receive, the guide 72 of the sleeve 28. Thechannel 74 extends at least along a portion of the distal portion 16. Inoperation, the guide 72 and channel 74 are configured to linearly, butnot rotationally, reciprocate relative to one another. It can beappreciated that the guide 72 may extend along the distal portion 16 ofthe housing 12 and the channel may be formed within the sleeve 28.

In another alternative embodiment, as shown in FIGS. 9A-C, the sleeve 28may have multiple segments with telescopic properties, such that, forexample, the sleeve 28 may consist of a base portion 38, a firsttelescoping portion 40, and a second telescoping portion 42. Thisconfiguration may allow the sleeve 28 to adjust to different lengths. Asshown in FIG. 9C, the first telescoping portion 40 is configured totelescope, or extend, from the base portion 38 in a distal direction,and the second telescoping portion 42 is configured to further telescopefrom the first telescoping portion 40. In alternative implementations,the distal portion 16 may also have a portion (not shown) with similartelescoping characteristics as this embodiment of the sleeve 28. It isalso contemplated that both the sleeve 28 and the distal portion 16 maybe configured to respectively telescope during operation within the sameembodiment. The sleeve 28 and/or the distal portion 16 may be retractedinto its original, or first, position upon completion of the operation.

A distal end 44 of the base portion 38 may be designed to prevent thefirst telescoping portion 40 from decoupling with the base portion 38.For example, FIGS. 9B and C are cross-sectional views of the sleeve 28in a retracted position and an extended position, respectively. Thedistal end 44 is flanged shaped and configured to abut a proximal end 46of the first telescoping portion 40. Using a similar configuration, adistal end 48 of the first telescoping portion 40 is configured to abuta proximal end 50 of the second telescoping portion 42, when the sleeve28 is in a fully extended position, as shown in FIG. 9C. It can beappreciated that the number, length, and diameter of the telescopingportions may vary and are application dependent. Accordingly, theoverall angular extension of the sleeve 28 can range anywhere between0-180°.

Independent of the configuration of the sleeve 28, the bone cutting tip56, in one embodiment, as shown in FIG. 3, is rotatably coupled with thedistal end 32 of the sleeve 28 by a coupling fastener 58. The couplingfastener 58 may include a c-clip 92 as shown in FIG. 10, a rotatablecoupler, or the like. The coupling fastener 58 couples the bone cuttingtip 56 to the distal end 32 of the sleeve 28 but permits relativerotational movement between the bone cutting tip 56 and the sleeve 28,as the bone cutting tip 56 is advanced through the medium.

Alternatively, a stop member 60 may be located along the length of theflexible shaft 26 as shown in FIG. 4. The stop member 60 may be locatedat a position adjacent to the proximal end 30 of the sleeve 28, and havea diameter substantially equal to or greater than the inner diameter ofthe sleeve 28, but less than the diameter of the passage 24. In thisembodiment, the bone cutting tip 56 is not directly coupled with thedistal end 32 of the sleeve 28, but instead is free to translate withrespect to the sleeve 28. However, the amount of relative axialtranslation between the sleeve 28 and the bone cutting tip 56 along theflexible shaft 26 is governed by the location of the stop member 60along the flexible shaft 26. For example, if the length of the flexibleshaft 26 between the stop member 60 and the bone cutting tip 56 issubstantially equal to the length of the sleeve 28, minimal relativetranslational movement between the sleeve 28 and bone cutting tip 56will exist. Conversely, if the length of the flexible shaft 26 betweenthe stop member 60 and the bone cutting tip 56 is greater than thelength of the sleeve 28, the bone cutting tip 56 will be permitted tohave limited relative translational movement between it and the distalend 32 of the sleeve 28. The displacement of the bone cutting tip 56with respect to the distal end 32 of the sleeve 28 will permit debrisand other medium fragments from being lodged in the tunnel 94 created bythe bone cutting tip 56. Instead, such debris and fragments will bedisplaced into the sleeve 28 and cleared away from the working area.

In one embodiment, the stop member 60, as shown in FIG. 11, has a outerportion 62 configured to abut the proximal end 30 of the sleeve 28 andan inner portion 64 adapted to receive the flexible shaft 26, with theouter 62 and inner 64 portions connected by a series of struts 66 whichradially extend from the inner portion 64 to the outer portion 62. Inthis configuration, a series of apertures 68 are formed within the stopmember 60, to enable debris and other fragments to pass through the stopmember 60 towards the proximal portion 14 of the housing 12. It can beappreciated that the number of struts 66 and apertures 68 may varydepending on the application.

The drill guide assembly 10 is intended to be used for arthroscopicsurgery. For example, the drill guide assembly 10 may be used forarthroscopic shoulder surgery, and specifically, for reattaching a tornrotator cuff tendon 82 back to a proximal end of a humerus 84, as shownin FIG. 1. The drill guide assembly 10 can be operated as a hand-helddevice, or alternatively, be configured to be coupled with a frame tofix the position of the drill guide assembly 10 once the entry portlocation is identified.

During the surgical procedure, a surgeon investigates the glenohumeraljoint by creating a posterior arthroscopic portal. An arthroscope (notshown) is introduced into the glenohumeral joint to an area proximate tothe damaged rotator cuff tendon. An anterior portal having a diameter of6 to 8 mm is made and an anterior cannula is inserted into the portal toperform a standard glenohumeral arthroscopy procedure. Once the damagedarea is identified, the arthroscope and anterior cannula arere-positioned to the subacrominal space, which is above the rotator cufftendon tear. A bursectomy is then preformed and the drill site isdetermined. A lateral port having an approximate diameter of 6 to 8 mmis made adjacent to the proximal end of the humerus 84 and the drillsite.

The drill guide assembly 10 is introduced through the lateral port andloosely placed against a far lateral portion of the humeral head. Theexit port locator 76 is extended from the first, retracted position, tothe second, extended, position, where the second end 80 of the exit portlocator 76 identifies the approximate exit port 96 location of thetunnel 94 to be formed by the bone cutting tip 56. The typical locationof the exit port 96 is located adjacent to the articular margin at themedial aspect of the rotator cuff footprint. Once the desired exit port96 location of the tunnel 94 is identified, the entry port site isdetermined. The fixed radius of curvature of the sleeve 28 and distalportion 16 permit the surgeon to accurately anticipate the path of thetunnel 94 formed by the bone cutting tip 56. The distal portion of thehousing 12 is then held firmly against the entry port 98 site, and theexit port locator 76 may be optionally retracted back to the firstposition. Alternatively, the exit port locator 76 may remain in thesecond, or extended, position during the remainder of the process, andthen be retracted once the drilling process is complete.

The flexible shaft 26 is advanced along with the bone cutting tip 56towards the entry port 98 site. The flexible shaft 26 and/or bonecutting tip 56 causes the sleeve 28 to advance therealong. In analternative embodiment, where the sleeve 28 is comprised of at least thefirst telescoping portion 40 and the second telescoping portion 42, theadvancement of the bone cutting tip 56 and/or flexible shaft 26 willcause the one of the first 40 and second 42 telescoping portions to moverelative to another.

The bone cutting tip 56 creates a tunnel 94 within the bone as it isadvanced and rotated by the flexible shaft 26. The bone cutting tip 56and the flexible shaft 26 travel along a path having a constant non-zeroradius of curvature between the first position to the second position.The radius of curvature of the tunnel 94 formed by the bone cutting tip56 is substantially equal to the radius of curvature of the sleeve 28and the distal portion 16 of the housing 12. The bone cutting tip 56,flexible shaft 26, and sleeve 28 are advanced through the bone until thebone cutting tip 56 reaches the second position, and exits the bone atthe predetermined exit port 96 site. The outer stop member 70 alsoprevents the bone cutting tip 56 from being advanced substantiallybeyond the exit port site.

In one embodiment, the diameter of the tunnel 94 created by the bonecutting tip 56 may be at least substantially equal to the externaldiameter of the distal portion 16 of the housing 12, thereby allowing aportion of the distal portion 16 of the housing 12 to enter the tunnel94 during the drilling process if additional angular displacement of thebone cutting tip 56 is necessary to form the tunnel 94 within the bone.Specifically, the distal portion 16 of the housing 12 may be partiallyinserted into the tunnel 94, thereby allowing the bone cutting tip 56 totunnel further through the bone, if necessary.

The rotation of the flexible shaft 26 and the bone cutting tip 56 mayimpart a rotational force on the sleeve 28, which may bind the sleeve 28against the distal portion 16 of the housing 12 if not constrained.However, the guide 72 and channel 74 arrangement prevents the rotationalrelative movement of the sleeve 28, but allow the sleeve 28 toreciprocate within the distal portion 16 of the housing 12. The guide 72and channel 74 arrangement may also function as a stop when the sleeve28 is fully extended from the distal portion 16 of the housing 12, wherethe guide 72 may abut an end of the channel 74 to restrict the travel ofthe sleeve 28 with respect to the distal portion 16 of the housing 12.

During the drilling process, bone fragments may be accumulate within thefreshly drilled tunnel 94 and may impede further drilling. Accordingly,in one embodiment, the gap between the bone cutting tip 56 and thedistal end 32 of the sleeve 28 may permit these fragments to exit fromthe drill site and into the sleeve 28. Moreover, these fragments andother debris may also exit through the proximal portion of the sleevevia the apertures 68 formed within the stop member 60.

Upon completion of the drilling process, the drill guide assembly 10 canbe removed by retracting the flexible shaft 26 and the bone cutting tip56 from the tunnels, from the second position back to the firstposition. The drill guide assembly 10 may then be removed from thecannula tube. A suture may then be shuttled through the tunnel 94 andpassed through the rotator cuff tendon using standard technique. Thesuture is tied to the rotator cuff tendon and secured to the bone. Thecannulas are removed and the portals are closed with simple sutures.

The drill guide assembly 10 may also be used to perform MedialPatello-Femoral Ligament (MPFL) reconstruction. During MPFLreconstruction, a medial patellofemoral ligament (MPFL) graft 86 isreattached, or resecured, to the patella 88, as shown in FIG. 12. Twotunnels 90 are created within the patella 88 which are used to securethe MPFL graft 86 to the patella 88.

To create the tunnels 90, a skin incision is made over the patella 88,and the superior, medial quadrant of the patella 88 is identified. Thedistal portion 16 of the drill guide assembly 10 is placed against themedial aspect of the patella 88 at a desired location of the entry portof the first tunnel. As explained above, with respect to the rotatorcuff tendon repair method, the desired exit port location of the firsttunnel may govern the location of the entry port of the tunnel.Accordingly, the exit port locator 76 may be extended from a first, orretracted position, to a second, or extended position, where the secondend 80 of the exit port locator 76 can approximate the location of theexit port of the tunnel located on the anterior patella surface, andthus locate the entry port location of the first tunnel.

Once the entry port location is identified, the bone cutting tip 56 maybe advanced in substantially the same method as described above tocreate the first and second tunnels 90 within the patella 88. Once thetunnels are created, an incision is made between the adductor tubercleand medial epicondyle and the desired location of femoral attachment ofthe MPFL graft 86 is located. An end of the MPFL graft 86 is doubledover and is secured to the femur with an interference screw. The twofree tails on the other end of the MPFL graft 86 are respectfullytunneled through the medical retinaculum and are brought though the twotunnels in the patella 88. The MPFL graft 86 is tensioned appropriatelyand the two tails are sutured back onto themselves to secure the graft.The incision is then closed with simple sutures.

In an alternative embodiment described below, the orthopedic guidedevice is configured to create tunnels using unique superelasticproperties of a material referred to commonly as “shape memory alloy.”The shape memory alloy is commonly made from nickel titanium (NiTi),sometimes referred to as “SMA,” also commonly known commercially asNitinol. In this embodiment, the guide tube is shaped having apre-formed non-zero radius of curvature. In this embodiment, and asshown in FIG. 13, a drill guide assembly 100 consists of a guide tube102 defining an A axis. The guide tube 102 comprises a proximal portion104, a distal portion 106, and a body portion 108 disposed between theproximal 104 and distal 106 portions. The relative lengths of theproximal 104, distal 106, and body 108 portions may vary betweenapplications, and may be dependent on the desired maneuverability andcharacteristics for a particular use.

In the embodiment shown in FIG. 13, the body portion 108 has asubstantially linear shape, however, the shape of the body portion 108may vary depending on the intended use of the assembly 100. For example,the body portion 108 may also have a shape having a non-zero radius ofcurvature, for improved ergonomics or to reduce the amount of strainexperienced by other components of the assembly 100.

As further shown in FIG. 13, a passage 110 is formed within the guidetube 102. The passage 110 generally extends from the proximal portion104 of the guide tube 102 to the distal portion 106 of the guide tube102, along the A axis. The passage 110 is configured to accommodate ahollow cutting tube 112 therein. The cutting tube 112 is slidablydisposed within the passage 110 of the guide tube 102 and canreciprocate within the passage 110. The cutting tube 112 includes adistal end 114 adjacent to the distal portion 106 of the guide tube 102and a proximal end 116 adjacent to the proximal portion 104 of the guidetube 102. A flexible driveshaft 118 is disposed within the cutting tube102 such that the driveshaft 118 is coupled with the hollow cutting tube112 but can rotate independently of the tube 112. A distal end 120 ofthe rotating driveshaft 118 is coupled with a bone cutting bit 124 and aproximal end 122 is configured to be attached to a driving mechanism,such as a pneumatic drill. The distal end 114 of the cutting tube 112 iscoupled with the driveshaft 118 and bone cutting bit 124 such that allthree components are designed to reciprocate with respect to the passage110 together while the driveshaft 118 and bone cutting bit 124 mayindependently rotate with respect to the cutting tube 112. The passage110 and/or an exterior surface of the cutting tube 112 may be coatedwith a lubricating compound, such as graphite or Teflon, or be made outof a material having a low coefficient of friction to reduce thefrictional force generated by the relative movement between the passage110 and the cutting tube 112.

The bone cutting tip 124 is disposed on the distal end 120 of thedriveshaft 118. The bone cutting tip 124 is designed to create a hole,or tunnel 94 as shown in FIG. 17, having approximately the same diameterof the bone cutting tip 124 through a medium, such as bone. As shown inFIGS. 1 and 2 the bone cutting tip 124 is fixedly coupled with thedistal end 120 of the driveshaft 118 via a bearing 123, with the bonecutting tip 124 being disposed adjacent to the distal end 114 of thecutting tube 112. The bone cutting tip 124 and the driveshaft 118 areconfigured to be able to rotate with respect to the cutting tube 112.The bone cutting tip 124 forms a hole having a diameter which is atleast equal to the outer diameter cutting tube 112, to permit thecutting tube 112 to be advanced through the hole or tunnel 94 formedwithin the working medium. The bone cutting tip 124 may be formed out ofany suitable metal alloy or plastic.

The hollow cutting tube 112 is comprised of a shape memory alloy. Ashape memory alloy enables the material to undergo a reversible phasetransformation when heated above its transition temperature and issuper-elastic once the transition temperature is reached and exceeded.Super-elastic infers that the material can endure greater changes instrain than standard engineering materials, such as steel or aluminum,while still returning to its initial shape when the deforming load isremoved (up to 8% in shape memory alloys versus around 0.5% in steels).In this application, the super-elastic effect of the shape memory alloyis desired, therefore, the transition temperature will be designed to bewell below room temperature (or whatever temperature range the productwill be designed for) to ensure the super-elastic effect of the materialwhen in use. The transition temperatures can be varied with thismaterial by changing the composition of the primary elements of thematerial (i.e., nickel and titanium). The cutting tube 112 may have apreformed shape as shown in FIG. 14, with a non-zero radius ofcurvature. When retracted, the cutting tube 112 may be deformed from itspre-formed shape into a new shape, such as one having a large radius ofcurvature or that is substantially linear as seen in FIG. 13. As thecutting tube 112 is extended, the material returns to its originalpre-formed shape due to the super-elastic property of the material. Onesuch shape memory alloy is comprised of Nickel and Titanium and iscommonly referred to as “Nitinol.” The hollow cutting tube 112 isconfigured to have a preformed shape of the desired tunnel to be formedwithin the humeral head of the patient, such that once it is extended,the tube 112 can return to this pre-formed curved shape, which is shownin FIG. 14. If the cutting tube 112 has a small preformed radius ofcurvature and if it is sufficiently elastic, it will allow the cuttingtube 112 to be inserted into a distal portion 106 with a larger radiusof curvature. The larger radius of curvature will reduce the overallinsertion profile, or width, of the distal portion 106 of the guide tube102 and enhance the ability to maneuver the guide tube 102 duringoperation.

The tube 112, in this embodiment, may have a radius of curvature of 15mm in its preformed shape and has an outer diameter of 3 mm. The radiusof curvature of outer diameter of the tube 112 is not limited to thesevalues, and may vary depending on the intended application.

For example, the preformed shape of the cutting tube 112 may have anarc-shape ranging from 0 to 360 degrees, and the fixed non-zero radiusof curvature may be 0 to 50 mm. However, the exact radius of curvaturedesired is dependent on the bone thickness and the intended use. Forexample, in the embodiment shown in FIG. 14 the cutting tube 112 has asemi-circular shape with a substantially constant radius of curvature,R.

The material of the cutting tube 112 may vary depending on theproperties desired for a particular procedure. Normally, metal alloyscan withstand a small degree of strain (or deflection) before they startto plastically yield (i.e. become permanently deformed), on the order of0.5%. When the cutting tube 112 is retracted inside the guide tube 102,the estimated strains created in the hollow alloy cutting tube 112 farexceed this value.

The maximum strain of the tube 112 with the aforementioned geometryconstraints can be calculated, to determine if using a retractablecurved tubing approach is practical. The maximum strain occurs when thetube 112 is retracted from its initial curved shape into a straightconfiguration.

Referencing the parameters set forth in FIG. 18, strain is defined asthe change in length divided by the original length of a material, asseen in equation 1 for this case, where L_(i1) is the arc length of theinner edge of the material in its curved state and L_(i2) is the lengthwhen it is extended.

$\begin{matrix}{\mspace{79mu} {{\text{?} = \frac{L_{i\; 2} - L_{i\; 1}}{L_{i\; 1}}}{\text{?}\text{indicates text missing or illegible when filed}}}} & \lbrack 1\rbrack\end{matrix}$

If it is assumed that the length of the centerline (L_(c)) does notchange, then for both the retracted and extended states L_(c) isdetermined as seen in equation 2, where R_(c) is the radius of curvatureat the centerline and θ is the angle of the arc (in radians).

L_(c)=R_(c)θ  [2]

If the tube 112 is extended perfectly straight, then L_(i2) is alsoequal to L_(c). L_(i1) can be calculated with equation 3, where θ is theangle of the arc (in radians) and D is the outer diameter of the tubing.

$\begin{matrix}{\mspace{79mu} {{{L\text{?}} = {\left( {R_{c} - \frac{D}{2}} \right)\text{?}}}{\text{?}\text{indicates text missing or illegible when filed}}}} & \lbrack 3\rbrack\end{matrix}$

Given the maximum allowable strain for the material, the equations canbe rearranged, as seen in equation 4, to calculate the largest diametertubing that will work with the given geometry restraints.

$\begin{matrix}{\mspace{79mu} {{D = {2{R_{c}\left( {1 - \frac{1}{1 + \text{?}}} \right)}}}{\text{?}\text{indicates text missing or illegible when filed}}}} & \lbrack 4\rbrack\end{matrix}$

Using a cutting tube diameter of about 2.5 mm, calculated strains equalabout 8%, which is much higher than normal alloy metals permit. Thiswould mean that normal alloys would plastically yield if they werecycled through this condition and the design approach described abovewould not be feasible.

However, a shape memory alloy, such as nickel titanium (NiTi), sometimesreferred to as “SMA,” also commonly known as Nitinol, derived from itsplace of discovery (Nickel Titanium Naval Ordnance Laboratory) mayovercome these obstacles.

This material has at least two unique properties: 1) the ability toundergo a reversible phase transformation when heated above itstransition temperature, and 2) super-elasticity. The former occurs whenthe material is initially below its transition temperature, and isdeformed or bent. If it is then heated above its transition temperature,it will return to its pre-deformed shape (at least to a degree).Conversely, if the SMA material is already above its transitiontemperature, it will be super-elastic, meaning that the material can bebent or deformed (strained) to a fairly significant degree, but stillreturn to its un-deformed shape once the applied loads are removed.While about 4%-6% recoverable strains are common, strains of up toapproximately 8% (ϵ=0.08) can be recoverable (i.e. the material can bedeformed that much and still return to its original shape).

The material is composed of approximately 46 to 55% nickel by weight.The phase transition temperature can be varied significantly by makingsmall changes in the composition of the elements. The Nitinol materialcan be composed such that it is super-elastic at room temperature (orwhatever operating temperature is specified).

Using equation 4 (above) and an 8% strain limit and initial radius ofcurvature of 15 mm, the diameter of the tubing can be up toapproximately 2.2 mm. Of course, the amount of strain limit and initialradius of curvature may be manipulated depending on the intended use.

In an alternative embodiment, if a larger cutting tube 112 diameter isrequired, instead of retracting the cutting tube 112 into asubstantially linear guide tube 102, the cutting tube 112 could beretracted into a larger tube 102 with a non-linear molded channel 128having an approximate diameter from 2-3 mm with a large radius ofapproximately 75 mm, so the cutting tube 112 does not have to be fullystraightened as shown in FIG. 19. The diameter of the channel 128 willvary depending on the application and may be greater or smaller than the2-3 mm channel disclosed in this embodiment. The curvature of the moldedchannel 128 reduces the tube strain allowing the preformed diameter ofthe tube 112 to be increased. The total guide tube 102 diameter may beapproximately 8.22 mm to fit through a standard cannula. Therefore, ifthe Nitinol tubing is only 2-4 mm in diameter, the diameter of themolded channel 128 may be increased to accommodate a non-linear designin order to significantly decrease the strain experienced by the cuttingtube 112 prior to being extended from the guide tube 102. Alternatively,the guide tube 102 may also be modified such that it has a non-zerosmall radius of curvature to reduce the amount of strain experienced bythe cutting tube 112 when it is in the retracted position. The radius ofcurvature of the guide tube 102 will not affect the ability of the guidetube 102 to be inserted through a standard arthroscopic portal.

In another embodiment shown in FIG. 110, the cutting tube 112 may bereplaced with a wire 130 made out of a memory shape alloy, such asNitinol, with the driveshaft 118 encircling the wire 130. In thisembodiment, the driveshaft 118 may be formed of a spring coil that wouldbe hollow inside. The wire 130, when extended, would cause thedriveshaft 118 to take on the curved preformed shape of the wire 130.The wire 130 would have less strain due to its smaller diameter.

In yet another embodiment, as shown in FIG. 21, the bone cutting bit 124at the distal end of the wire 130 may be replaced with a piercing needle132 to penetrate the bone medium. A pneumatic impact driver, such as animpact gun, drives the wire 130 to create a tunnel within the bonemedium. The impact of the piercing needle 132 removes fragments of thebone in order to create the curved tunnel 94. There is minimal relativerotation between the wire 130 and the channel 128 order to create thetunnel. Therefore, a driveshaft to rotate the wire 130 may not benecessary in this particular embodiment. Also, the channel 128 may alsohave a non-zero radius of curvature along its length to reduce theamount of strain on the wire 130.

During the surgical procedure, a surgeon investigates the glenohumeraljoint by creating a posterior arthroscopic portal. An arthroscope (notshown) is introduced into the glenohumeral joint to an area proximate tothe damaged rotator cuff tendon. An anterior portal having a diameter of6 to 8 mm is made and an anterior cannula is inserted into the portal toperform a standard glenohumeral arthroscopy procedure. Once the damagedarea is identified, the arthroscope and anterior cannula arerepositioned to the subacrominal space, which is above the rotator cufftendon tear. A bursectomy is then preformed and the drill site isdetermined. A lateral port having an approximate diameter of 6 to 8 mmis made adjacent to the proximal end of the humerus 84 and the drillsite.

During the surgical procedure, the lateral port is created insubstantially the same way as described above. Then, the drill guideassembly 100 is introduced through the lateral port and loosely placedagainst a far lateral portion of the humeral head 84 through a cannula126. During an arthroscopic procedure, the cutting tube 112 and flexibledriveshaft 118 are retracted inside the guide tube 102 and locatedadjacent to the intended drill site as shown in FIG. 13. In thisembodiment, the cutting tube 112 is above its transition temperature andtherefore is super-elastic. However, it is contemplated that the phasechange may occur during the procedure so as to permit portions of thecutting tube 112 to transition to being super-elastic once extended fromthe guide tube 102. However, in this embodiment, the cutting tube 112 isabove the transition temperature and therefore in its super-elasticphase prior to placing the assembly 100 adjacent to the humeral head.After inserting this assembly 100 into the cannula 126, the surgeonwould locate the drill tool at the desired location on the humeral head84 and then actuate the tool. Upon actuation, the cutting tube 112 wouldslowly be extended out of the guide tube 102 while the flexibledriveshaft 118 and cutting bit 124 rotate. The flexible driveshaft 118and cutting bit 124 would extend along with the cutting tube 112, withthe cutting bit 124 creating a tunnel 94 in the bone as it movesforward. As extended beyond the guide tube 102, the shape of the hollowcutting tube 112 will be permitted to take on its initially pre-formedshape, as shown in FIG. 14. As the cutting tube 112 continues to extend,a curved tunnel 94 would be created in the humeral head 84 as shown inFIG. 16 having a shape similar to that of the pre-formed shape of thehollow cutting tube 112.

Upon completion of the drilling process, the drill guide assembly 100can be removed by retracting the cutting tube 112, driveshaft 118, andthe bone cutting tip 124 from the tunnel 94 as shown in FIG. 17. If thepreformed shape of the cutting tube 112 inhibits it from being retractedback into the guide tube 102, the drill guide assembly 100 may beremoved form the cannula tube 126 without retracting the cutting tube112 into the guide tube 102.

Once the drill guide assembly 100 is removed from the cannula tube 126,a suture may then be shuttled through the tunnel 94 and passed throughthe rotator cuff tendon using standard technique. The suture is tied tothe rotator cuff tendon and secured to the bone. The cannulas areremoved and the portals are closed with simple sutures.

It can be appreciated that the drill guide assembly 100 may also be usedto perform other medical procedures requiring a substantially curvedtunnel. For example, the assembly 100 can be used to perform MedialPatello-Femoral Ligament (MPFL) reconstruction. During MPFLreconstruction, a medial patellofemoral ligament (MPFL) graft isreattached, or resecured, to the patella. Two tunnels are created withinthe patella which are used to secure the MPFL graft to the patella.

1-20. (canceled)
 21. A method for drilling, the method comprising,providing a drill guide having a housing having a proximal portion and acurved distal portion having a distal end and a radius of curvature, anda flexible shaft disposed in the assembly having a distal end comprisinga piercing member: determining a drill site on the bone; positioning thedistal end of the housing adjacent to the drill site on the bone;advancing the flexible shaft and the piercing member toward the drillsite; and creating an opening within the bone using the piercing member,wherein a radius of curvature of the opening is substantially equal tothe radius of curvature of the curved distal portion of the housing. 22.The method of claim 21, further comprising the step of engaging an outerstop member, located on the flexible shaft, with the housing to limit adistance of travel of the flexible shaft within the housing.
 23. Themethod of claim 21, further comprising retracting the flexible shaft andthe piercing member from the opening within the bone.
 24. A method fordrilling, the method comprising, providing a drill guide having ahousing having a proximal portion and a curved distal portion having adistal end and a radius of curvature, and a flexible shaft configured tobe disposed in the assembly having a distal end comprising a piercingmember: determining a drill site on the bone; positioning the distal endof the housing adjacent to the drill site on the bone; inserting theflexible shaft and the piercing member into the housing; advancing theflexible shaft and the piercing member toward the drill site; andextending the flexible shaft and the piercing member from the distal endof the housing such that the piercing member maintains the radius ofcurvature of the distal portion of the housing; and creating an openingwithin the bone using the piercing member, wherein a radius of curvatureof the opening is substantially equal to the radius of curvature of thecurved distal portion of the housing.
 25. The method of claim 24,further comprising the step of engaging an outer stop member, located onthe flexible shaft, with the housing to limit a distance of travel ofthe flexible shaft within the housing.
 26. The method of claim 24,further comprising retracting the flexible shaft and the piercing memberfrom the opening within the bone.
 27. A method for drilling, the methodcomprising, providing a drill guide having a housing having a proximalportion and a curved distal portion having a distal end and a radius ofcurvature, a flexible shaft disposed in the assembly and having a distalend comprising a piercing member, a sleeve disposed around the flexibleshaft, wherein the flexible shaft is configured to be slidingly disposedwithin the sleeve: determining a drill site on the bone; positioning thedistal end of the housing adjacent to the drill site on the bone;advancing the flexible shaft and the piercing member toward the drillsite, causing the sleeve to advance therealong; extending the sleeve andat least a portion of the piercing member from the distal portion of thehousing such that the sleeve and the piercing member maintain the radiusof curvature of the distal portion of the housing; and creating anopening within the bone using the piercing member, wherein a radius ofcurvature of the opening is substantially equal to the radius ofcurvature of the curved distal portion of the housing.
 28. The method ofclaim 27, further comprising the step of engaging an outer stop member,located on the flexible shaft, with the housing to limit a distance oftravel of one of the flexible shaft and the sleeve within the housing.29. The method of claim 27, further comprising retracting the flexibleshaft the piercing member, and the sleeve from the opening within thebone.